Start on "Hero".

Well, I wouldn't say he's weak. Immediately level up Skilled Chaos + Pyromancy. Look for the Phoenix Feather Cloak near the castle or in the shop. At the beginning of the game, also set a random artifact bonus – maybe you'll get lucky. Mages don't have mana problems.

I remember how, in the first week, they had to defeat about 70 or more red crossbowmen. There was no guild yet, nor Guild Battle Points. I put 7 gargoyles, each with 1 unit, into the battle. The crossbows split into 4 squads. I destroyed 2 stacks at a time with a Fireball and won the battle with almost no losses.

And against high-level creatures, the damage from the Fireball isn't as important as the 50% defense reduction.